Right now gw2 has def class variation hp / def making some classes much more glassly the other but there is no variation on power / precision the main dmg effect.
I suggest you do away with hp / def class variation and make it a pure build effect OR you add variation to power / precision (lowest hp / def gives you highest base power / precision).
This 1/2 balances they have now is not working and often lets high def classes "cheat" by letting them build more dmg aimed.
This was not a problem with the core classes as they where balances with the hp / def and dmg effect in mind but eliet spec have throw this comply out of wack where you have super glassly classes needing to go into melee ranged and doing minimal dmg at high risk and made super tankly classes able to do high dmg from long ranged doing max dmg at minimal risk. Its only going to get worst as they add in more elite spec.
See ELE forms and you will get my views.